The present invention relates to a contacting device for a chip card wherein the term chip card also includes so-called IC cards or a SIM (subscriber identity module). In any case, the chip card has a chip (a contact image) with corresponding contact surfaces which, when the card is inserted, are contacted in the contacting device with corresponding contacts of the contacting device.
A known contacting device comprises a housing with a housing body, in which contacts for contacting corresponding contact surfaces on the chip card are arranged, and a cover, which is (usually) pivotably connected to the housing body, for receiving the chip card, wherein the cover, after being pivoted against the base body and subsequent parallel displacement relative to the base body, can be locked therewith. The cover can be of a single-part or multi-part construction so that in the following the term cover is always to be understood also in the sense of a cover part.
Such a contacting device is known in practice.
A similar contacting device is described in EP 0 472 692 B1. In order to indicate the locked state, the known contacting device has two separate switching contacts as well as a short circuit bridge arranged in the cover.
The disadvantage of this device is that the locked state between the cover and the housing body is indicated also when no chip card is present.
When manufacturing the contacting device, the contacts, including the switching contacts, are soldered onto a corresponding printed circuit board. This is carried out with the cover being closed (locked). Accordingly, the known device has a further disadvantage in that during the soldering process of the contacting device on a printed circuit board the switching contacts are mechanically and thermally loaded and this results in a loss of contacting power.
EP 0 595 305 B1 describes an IC card reader with a switch comprised of two switching contacts. As in the configuration of EP 0 472 692 B1, there is also one objection to be raised in this case in that two switching contacts are necessary.
DE 197 43 937 A1 discloses a contacting device for a SIM card with an indicator for the presence of a card wherein, however, the indicator is already activated when the cover is not yet in its locking position. This can result in operational errors.
The invention has the object to provide a contacting device of the aforementioned kind which is of a simple configuration and is activate exclusively in the operations position.
The principal idea of the invention is to design and arrange the switching contact such that it is activated exclusively when the chip card is inserted and the cover is locked. For this purpose, the switching contact can be brought into a first contact position with corresponding contact locations on a correlated printed circuit board by means of the chip card, for example, inserted into the cover, when placing the cover onto the housing body. However, according to the invention, this first contact position is designed to remain electrically ineffective. The gist of the invention also furthermore presupposes in this respect that the switching contact, when locking the cover relative to the housing body, is brought into a second contact position in which the switching contact is electrically activated wherein this second contact position, for example, can be short-circuited with the aid of the switching contact.
Based on the contacting device of the aforementioned kind, the invention therefore provides a switching contact arranged in the cover which is designed and arranged such that it is electrically activated exclusively when the chip card is inserted and the cover is locked on the housing body.
In this context, the switching contact can co-operate with a first contact location and a second contact location which are arranged perpendicularly to the displacement direction of the cover in a plane parallel to the cover at a spacing to one another in the locking position wherein the contact locations end at the same location in the displacement direction of the cover, wherein, however, one of the contact locations is shorter than the other.
In this embodiment the switching contact therefore rests against only one contact location in the afore described first contact position. The switching contact reaches both contact locations at the same time only upon displacement of the cover into the locking position so that it is only now electrically activated (for example, short-circuited).
In order to keep the wear of the switching contact, especially during displacement of the cover into the locking position, as minimal as possible, an alternative embodiment suggests to design both contact locations in the same form size), but to divide one contact location into an electrically not activatable portion and an electrically activatable portion, wherein the electrically activatable portion is positioned in front of the electrically not activatable portion in the displacement direction of the cover.
In this embodiment it is prevented that the switching contact during the displacement movement of the cover must ascend onto the contact location which is elevated, if only by a minimal amount. Instead, in this embodiment it is achieved that the switching contact glides along a defined plane wherein this plane has the aforementioned two contact positions.
This second embodiment is especially advantageous when a slotted switching contact is used. In this context, the term xe2x80x9cslottedxe2x80x9d switching contact is to be understood in the sense that the switching contact is still of a single-part construction but has a penetration (a slot) in the axial direction so that, for example, parallel extending portions are formed which are connected at their ends by the switching contact material.
The two contact positions described above in detail can also be realized by means of a switching contact which has two contact zones spaced apart (arranged one after another) in the axial direction wherein, in analogy to the above description, the activation occurs only in the second contact position. The contact locations on the printed circuit board are then also arranged one after another.
Configurational problems may occur because of the limited spatial conditions in such a contacting device and a minimum spacing between the adjacently positioned contact locations of the printed circuit board.
Accordingly, a contacting device is proposed in which the legs (switching contact legs) are formed in the direction toward the correlated contact locations in an asymmetrically convex configuration such that the contact portions of the legs cooperating with the contact locations have a greater spacing relative to one another in comparison to a shape that is symmetrically convex relative to the central longitudinal axis of the legs.
By enlarging the spacing of the contact portions of the two legs of the switching contacts, the spacing of the correlated contact locations on the printed circuit board can be enlarged accordingly and the safety of the contacting device can thus be increased.
Simultaneously, by providing a convex configuration of the legs, a safe contacting on the corresponding contact locations is ensured.
The switching contact is arranged in the cover and can be, for example, embedded in the insulating material of the cover with portions thereof by injection molding or can be pressed onto or snapped into the cover. According to one embodiment, when the cover is open (without card), the free end (contact end) is designed to project into the space which is occupied by the chip card in the operational position. This position is to be maintained by the switching contact even when the cover (without card) is closed. Conversely, when the card is inserted, the card pushes the switching contact away into the first, electrically inoperable contact position (as soon as the cover is placed onto the housing body but is not yet locked thereto).
A further embodiment suggests that the switching contact is arranged and embodied such that it is not mechanically loaded even when the cover is closed and locked but no chip card is inserted.
For this purpose, a cover surface can have an opening into which the free contact end projects if no chip card is inserted in the device. This has the advantage that the contacting device can be soldered without mechanical tensioning of the switching contact onto a corresponding printed circuit board.
A control edge of the switching contact, i.e., the edge which is loaded by the chip card, can be embodied so as to be electrically insulated. This means that a short circuit between the card and the switching contact can be reliably prevented because the short circuit bridge (second contact position of the switching contact) will take on the potential of the contact locations on the printed circuit board when switching takes place.
In comparison to the aforementioned EP 0 472 692 B1 the following advantages result:
Instead of two switching contacts only a single switching contact is required. The switching contact can be activated only with inserted card and in the locked state of the contacting device. In this context, the chip card can be arranged in a corresponding recess in the housing cover but also within the housing body. When soldering the contacting device onto a correlated printed circuit board (with locked cover, but without card), the switching contact is mechanically not loaded.
Further features of the invention result from the features of the dependent claims as well as the other application documents.